I don't think its an ESP, I think its a parts bass with an ESP neck. In the early days esp was a parts company, They sold parts to a lot of small guitar companies that made high end guitars, and even some big name brands from the 80's/90's were using them. I belive you could order ESP parts thru certain dealers, the necks were stamped on the back like yours. I think the logo on the front is either a waterslide or a stencil that someone added along the way. Either way it definitley looks like an ESP neck to me. Schallers and the baddass are great parts, but they also lead me to belive this was a parts guitar, since I think ESP made their own hardware on the early stuff. The body I don't know, I could be anything, can't see enough from the pictures. If i was a 48th street custom, it would say 48th street custom on the headstock, if it was an early ESP assembled by the 48th street custom shop (these a fairly common), It would have an esp logo on the front and they would have signed the neck heal 48Th, if the body is an old esp parts body if will probably have a large ESP ink stamp in the neck pocket. To me you have an ESP neck, with damn nice tuners and a nice bridge. looks like who ever put this togther knew what they were doing and it probably has decent quality body, an electronics. To me if It feels right to you thats the most important part.